Search

Human lungs contain secretory leukocyte protease inhibitor (SLPI), elafin and its biologically active precursor trappin-2 (pre-elafin). These important low-molecular weight inhibitors are involved in controlling the potentially deleterious proteolytic activities of neutrophil serine proteases including elastase, proteinase 3 and cathepsin G. We have shown previously that trappin-2, and to a lesser extent, elafin can be linked covalently to various extracellular matrix proteins by tissue transglutaminases and remain potent protease inhibitors. SLPI is composed of two distinct domains, each of which is about 40% identical to elafin, but it lacks consensus transglutaminase sequence(s), unlike trappin-2 and elafin. We investigated the actions of type 2 tissue transglutaminase and plasma transglutaminase activated factor XIII on SLPI. It was readily covalently bound to fibronectin or elastin by both transglutaminases but did not compete with trappin-2 cross-linking. Cross-linked SLPI still inhibited its target proteases, elastase and cathepsin G. We have also identified the transglutamination sites within SLPI, elafin and trappin-2 by mass spectrometry analysis of tryptic digests of inhibitors cross-linked to mono-dansyl cadaverin or to a fibronectin-derived glutamine-rich peptide. Most of the reactive lysine and glutamine residues in SLPI are located in its first N-terminal elafin-like domain, while in trappin-2, they are located in both the N-terminal cementoin domain and the elafin moiety. We have also demonstrated that the transglutamination substrate status of the cementoin domain of trappin-2 can be transferred from one protein to another, suggesting that it may provide transglutaminase-dependent attachment properties for engineered proteins. We have thus added to the corpus of knowledge on the biology of these potential therapeutic inhibitors of airway proteases.

International audience; Respiratory diseases affect millions of people worldwide, and account for significant levels of disability and mortality. The treatment of lung cancer and asthma with therapeutic antibodies (Abs) is a breakthrough that opens up new paradigms for the management of respiratory diseases. Antibodies are becoming increasingly important in respiratory medicine; dozens of Abs have received marketing approval, and many more are currently in clinical development. Most of these Abs target asthma, lung cancer and respiratory infections, while very few target chronic obstructive pulmonary disease-one of the most common non-communicable causes of death-and idiopathic pulmonary fibrosis. Here, we review Abs approved for or in clinical development for the treatment of respiratory diseases. We notably highlight their molecular mechanisms, strengths, and likely future trends.

International audience; Tissue factor pathway inhibitor-2 (TFPI-2) is a potent inhibitor of plasmin which activates matrix metalloproteinases (MMPs) involved in degradation of the extracellular matrix. Its secretion in the tumour microenvironment makes TFPI-2 a potential inhibitor of tumour invasion and metastasis. As demonstrated in aggressive cancers, TFPI-2 is frequently down-regulated in cancer cells, but the mechanisms involved in the inhibition of tumour progression remained unclear. We showed in this study that stable TFPI-2 down-regulation in the National Cancer Institute (NCI)-H460 non-small cell lung cancer cell line using specific micro interfering micro-interfering RNA promoted tumour progression in a nude mice orthotopic model that resulted in an increase in cell invasion. Moreover, TFPI-2 down-regulation enhanced cell adhesion to collagen IV and laminin via an increase in alpha(1) integrin on cell surface, and increased MMP expression (mainly MMP-1 and -3) contributing to cancer cell invasion through basement membrane components. This study also reveals for the first time that pulmonary fibroblasts incubated with conditioned media from TFPI-2 silencing cancer cells exhibited increased expression of MMPs, particularly MMP-1, -3 and -7, that are likely involved in lung cancer cell invasion through the surrounding stromal tissue, thus enhancing formation of metastases.

International audience; Tissue factor pathway inhibitor-2 (TFPI-2) is a Kunitz-type serine proteinase inhibitor that inhibits plasmin-dependent activation of several metalloproteinases. Downregulation of TFPI-2 could thus enhance the invasive potential of neoplastic cells in several cancers, including lung cancer. In this study, TFPI-2 mRNA was measured using a real-time PCR method in tumours of 59 patients with non-small-cell lung cancer (NSCLC). Tumour TFPI-2 mRNA levels appeared well correlated with protein expression evaluated by immunohistochemistry and were 4-120 times lower compared to those of nonaffected lung tissue in 22 cases (37%). Hypermethylation of the TFPI-2 gene promoter was demonstrated by restriction enzyme-polymerase chain reaction in 12 of 40 cases of NSCLC (30%), including nine of 17 for whom tumour TFPI-2 gene expression was lower than in noncancerous tissue. In contrast, this epigenetic modification was shown in only three of 23 tumours in which no decrease in TFPI-2 synthesis was found (P ¼ 0.016). Decreased TFPI-2 gene expression and hypermethylation were more frequently associated with stages III or IV NSCLC (eight out of 10, P ¼ 0.02) and the TFPI-2 gene promoter was more frequently hypermethylated in patients with lymph node metastases (eight out of 16, P ¼ 0.02). These results suggest that silencing of the TFPI-2 gene by hypermethylation might contribute to tumour progression in NSCLC.

Tissue factor pathway Inhibitor-2 (TFPI-2) is associated with extracellular matrices and plays a major role in cell migration and tumor invasion. In this study, a 4.8-kb human TFPI-2 gene 5'-flanking region was isolated, cloned and sequenced. Promoter region analysis revealed a high GC-rich content without canonical TATA and CAAT boxes but three transcription initiation sites were identified. Moreover, several putative binding sites for transcription factors were identified (MyoD, LYF1, NF-Y, GATA, oct-1, AP-1, Sp1, NF1, NF-kappa B and egr-1). To characterize potential regulatory regions, TFPI-2/luciferase promoter constructs were then transfected in human choriocarcinoma JEG-3 cells. We first showed that the minimal TFPI-2 promoter is located between -166 and -111 from the translation start site. Luciferase activity consistently increased after stimulation of JEG-3 cells by phorbol 12-myristate 13-acetate indicating that NF1, NF-kappa B and egr-1/Sp1 binding sites are crucial in inducible TFPI-2 expression. Moreover, negative regulatory regions included AP-1 binding sites were identified. This study demonstrates that the TFPI-2 gene promoter exhibits typical features of a housekeeping gene.

International audience; Cysteine cathepsins have emerged as new players in inflammatory lung disorders. Their activities are dramatically increased in the sputum of cystic fibrosis (CF) patients, suggesting that they are involved in the pathophysiology of CF. We have characterized the cathepsins in CF expectorations and evaluated their use as markers of colonization by Pseudomonas aeruginosa. The concentrations of active cathepsins B, H, K, L and S were the same in P. aeruginosa-positive (19 Ps+) and P. aeruginosa-negative (6 Ps-) samples, unlike those of human neutrophil elastase. Also the cathepsin inhibitory potential and the cathepsins/cathepsin inhibitors imbalance remained unchanged and similar (∼2-fold) in the Ps+ and Ps- groups (p

Kallikrein-related peptidases (KLKs) are an emerging group of secreted serine proteases involved in several physiological and pathological processes. We used a degradomic approach to identify potential substrates of KLK12. MDA-MB-231 cells were treated either with KLK12 or vehicle control, and the proteome of the overlying medium was analyzed by mass spectrometry. CCN1 (cyr61, ctgf, nov) was among the proteins released by the KLK12-treated cells, suggesting that KLK12 might be responsible for the shedding of this protein from the cell surface. Fragmentation of CCN1 by KLK12 was further confirmed in vitro, and the main cleavage site was localized in the hinge region between the first and second half of the recombinant protein. KLK12 can target all six members of the CCN family at different proteolytic sites. Limited proteolysis of CCNs (cyr61, ctgf, nov) was also observed in the presence of other members of the KLK family, such as KLK1, KLK5, and KLK14, whereas KLK6, KLK11, and KLK13 were unable to fragment CCNs. Because KLK12 seems to have a role in angiogenesis, we investigated the relations between KLK12, CCNs, and several factors known to be involved in angiogenesis. Solid phase binding assays showed that fragmentation of CCN1 or CCN5 by KLK12 prevents VEGF(165) binding, whereas it also triggers the release of intact VEGF and BMP2 from the CCN complexes. The KLK12-mediated release of TGF-β1 and FGF-2, either as intact or truncated forms, was found to be concentration-dependent. These findings suggest that KLK12 may indirectly regulate the bioavailability and activity of several growth factors through processing of their CCN binding partners.

Chicken egg ovoinhibitor is a multidomain Kazal-type serine protease inhibitor with unknown function. Comparison of expression between different tissues indicated that ovoinhibitor is highly expressed in the magnum and liver followed by the uterus, which secrete egg white, egg yolk, and eggshell precursors, respectively. The results also revealed that ovoinhibitor expression is increased in the liver during sexual maturation followed by a subsequent decrease in mature hens. Ovoinhibitor was purified from the egg yolk plasma from nonfertilized eggs using two consecutive affinity chromatographies and gel filtration. Purified egg yolk ovoinhibitor was shown to inhibit trypsin and subtilisin. It was shown that purified egg yolk ovoinhibitor exhibited antimicrobial activities against Bacillus thuringiensis . The results suggest that this anti-protease plays a significant role in antibacterial egg defense against Bacillus spp., preventing contamination of table eggs (nonfertilized eggs) and protecting the chick embryo (fertilized eggs).

The oligodendrocyte myelin glycoprotein (OMgp) inhibits axon regeneration after injury in the adult mammalian central nervous system. However its function during brain development remains largely unknown. The present study aims to analyze a possible role for OMgp during neurogenesis. We showed that neural stem cells (NSC) extracted from the whole mesencephalon of rat embryos (E14) and cultured as free floating neurospheres expressed both OMgp and its receptor Nogo-R1. An over-expression of OMgp affected NSC expansion by reducing cell proliferation, but did not affect their differentiation into neurons. These findings indicate a new role for OMgp during brain development as a possible regulator of neurogenesis. Moreover, they suggest a possible implication for OMG gene in the etiology of neurofibromatosis type 1 forms characterized by a deletion of the NF1 gene locus containing OMG.

Most housekeeping genes, tumor-suppressor genes, and approx 40% of tissue-specific genes contain G+C sequences in their promoter region that were very difficult to amplify. In this report, we propose an improved polymerase chain reaction (PCR) method to be used for successful amplification of the tissue factor pathway inhibitor (TFPI)-2 gene promoter region that exhibit >70% G+C content in a sequence of approx 300 bp and a complete CpG island region spanning exon 1, the three transcription initiation sites, and the translation start site. Therefore, this method can be recommended to amplify other GC-rich genomic templates.

International audience; Computer model of the interaction of human TFPI-2 Kunitz-type serine protease inhibitor with human plasmin Dear Sir, Tissue factor pathway inhibitor-2 (TFPI-2) is a 32-kDa serine proteinase inhibitor that strongly inhibits trypsin, plasmin, factor XIa and plasma kallikrein [1], and is mainly associated with extracellular matrices [2]. By inhibiting plasmin, TFPI-2 thus efficiently decreases activation of several metalloproteinases [2] and reduces tumor invasion and metastasis [3,4]. In addition, TFPI-2 can also regulate plasmin in atherosclerotic plaques by modulating extracel-lular proteolytic mechanisms [5]. TFPI-2, which is a member of the Kunitz-type serine proteinase inhibitor family, consists of three tandemly repeated Kunitz-type domains, the first of which (K1) exhibits similarities in amino acid sequence to TFPI-1 and bovine pancreatic trypsin inhibitor (BPTI) (45% and 40%, respectively). The inhibition of serine proteinases by Kunitz-type inhibitors involves their binding to K1 and P1 residue that interacts with the proteinase pocket previously identified to be an arginine or a lysine residue [6-9]. Using site-directed mutagenesis experiments, Kamei et al. [10] reported that a TFPI-2 mutant with glutamine substituted for arginine lost its inhibitory activity towards trypsin and plasmin. Several structures showing the interaction of one serine proteinase with a Kunitz-type inhibitor, i.e. thrombin with BPTI [6], factor Xa/VIIa with TFPI-1 [7,8] and alpha-chymotrypsin with BPTI [9], have been determined crystallographically. However , TFPI-2 structure and plasmin complexed with a Kunitz-type inhibitor have not to date been described. This report is the first to address the structural basis for molecular recognition of plasmin by the K1 domain of TFPI-2 (TFPI-2/K1). The 3D models of TFPI-2/K1 was built using the automatic comparative modeling server swissPDB (http:// www.expasy.org). The structure of TFPI-1/K2 (44% identity with TFPI-2/K1 in 55 residues) was used as template to determine TFPI-2/K1. The resulting model was further energy-minimized using the steepest descent algorithm (SYBYL 6.9, Tripos, http://www.tripos.com), the atoms of the backbone being constrained during this step, and un-constrained using the conjugate gradient algorithm until the maximum derivative was < 0.1 kcal/mol/A ˚. After checking the stereochemical quality (WHATIF, http://www.cmbi. kun.nl/), all parameters were good for ensemble structure. The TFPI-2/K1 model and plasmin (coordinates extracted from the PDB file 1 bml) were superimposed on the Ca atoms of the TFPI-1/trypsin complex (coordinates extracted from the PDB file 1tfx). Finally, the few atoms that overlapped at the complex interface were relieved by energy minimization. The electrostatic potentials of TFPI-2/K1 and plasmin were calculated with swissPDB viewer 3.7b software and using formal charges at pH 7.4 (arginine, lysine, N-terminus, + 1; glutamate, aspartate and the C-terminus, À 1; and histidine, neutral), ionic strength in the aqueous environment of 0.15 M and dielectric constant of 80. The three-dimensional structure of TFPI-2/K1 exhibited the typical Kunitz-type proteinase inhibitor folding, i.e. a double stranded anti-parallel h-sheet from Arg20 to Phe33, and an a-helix from Trp48 to Ala54. The core of the domain, comprising the secondary structure elements and the three disulfide bonds, was highly conserved. TFPI-2/K1 exhibited the same overall fold as BPTI [6] and TFPI-1/K2 [7], with rms deviations (root-mean-square) for all 55 Ca atom positions of 0.70 and 1.09 A ˚ , respectively. These values are in agreement with the 40% identity with BPTI and 45% identity with TFPI-1/K2. The binding loop of TFPI-2/K1 (Leu19-Tyr33) was in direct contact with the active site of plasmin involving the characteristic main-main conforma-tional and intermolecular hydrogen bond interactions of canonical binding proteinase inhibitors [7-9]. Indeed, as shown in Table 1, TFPI-2/K1 residues positioned close to the active site of plasmin (PV2, PV1, P1 and P3 residues) were involved in hydrogen bonds. As compared with the TFPI-1/trypsin complex [7], two additional hydrogen bonds were found at the interface between TFPI-2/K1 and plasmin, probably improving the complementarity between the two molecules. The side-chain of TFPI-2 P1 residues (Arg15) extended into the plasmin-specific pocket, with its guanidi-nium group forming a salt bridge with the carboxylate group 0049-3848/$-see front matter D

Background The c-myb proto-oncogene is the founding member of a family of transcription factors involved principally in haematopoiesis, in diverse organisms, from zebrafish to mammals. Its deregulation has been implicated in human leukaemogenesis and other cancers. The expression of c-myb is tightly regulated by post-transcriptional mechanisms involving microRNAs. MicroRNAs are small, highly conserved non-coding RNAs that inhibit translation and decrease mRNA stability by binding to regulatory motifs mostly located in the 3'UTR of target mRNAs conserved throughout evolution. MYB is an evolutionarily conserved miR-150 target experimentally validated in mice, humans and zebrafish. However, the functional miR-150 sites of humans and mice are orthologous, whereas that of zebrafish is different. Results We identified the avian mature miRNA-150-5P, Gallus gallus gga-miR-150 from chicken leukocyte small-RNA libraries and showed that, as expected, the gga-miR-150 sequence was highly conserved, including the seed region sequence present in the other miR-150 sequences listed in miRBase. Reporter assays showed that gga-miR-150 acted on the avian MYB 3'UTR and identified the avian MYB target site involved in gga-miR-150 binding. A comparative in silico analysis of the miR-150 target sites of MYB 3'UTRs from different species led to the identification of a single set of putative target sites in amphibians and zebrafish, whereas two sets of putative target sites were identified in chicken and mammals. However, only the target site present in the chicken MYB 3'UTR that was identical to that in zebrafish was functional, despite the additional presence of mammalian target sites in chicken. This specific miR-150 site usage was not cell-type specific and persisted when the chicken c-myb 3'UTR was used in the cell system to identify mammalian target sites, showing that this miR-150 target site usage was intrinsic to the chicken c-myb 3'UTR. Conclusion Our study of the avian MYB/gga-miR-150 interaction shows a conservation of miR-150 target site functionality between chicken and zebrafish that does not extend to mammals.